While trawling Wiki earlier today I stumbled upon the maddest fact I have ever heard of:

"Grand Dieu Sauve Le Roi", was written by Jean-Baptiste Lully to celebrate the healing of Louis XIV's anal fistula.

Right, let that morsel sink in. The man wrote a song to celebrate the healing of the King's bottom?!? ..... Totally random. Come on then people, I invite you to startle me with your song related facts - If you can come up with an odder one than this then I shall doff my hat to you :D